Illuminated transit



' I D. W. BRUNTON.

, ILLUMINATED TRANSIT.

APPLICATION r1151) SEPT- 15. 1911.

1,339,019, P11011161 May 4; 1920.

DAVID W. BRUNTON, QF DENVER, 'GOLORADG.

ILLUMINATED TRANSIT.

Specification of Letters Patent. Patented May 4,, 19249,

Application filed September 15, 1917. Serial No. 293,559.

To all whomit may concern:

Be it known that 1, DAVID W. BRUNTON, a citizen of the United States, residin at Denver, in the county of Denver and tate of Colorado, have invented a certain new and useful Improvement in Illuminated Transits, of which the following is a full, clear, and exact description.

The object of this invention is to provide a transit, compass or the like with means whereby it is adapted for use either in the light or in the dark, and it has reference particularly to the pocket transit of my Patents No. 526,021, dated September 18, 1894:, No. 1,042,079, dated October 22, 1912, No. 1,062,582, dated May 27, 1913, and No. 1,092,822, dated April 14:, 1914.

The invention consists in a transit, compass or the like having a transparent cover plate provided with luminous indicia rendered non-diffusive with reference to the interior of the instrument so that the instrument may be used for surveying or marchingat night or in the dark, without in the least impairing its usefulness in the light,

as I will proceed now to explain and finally claim.

In the accompanying drawings illustrating the invention, in the several figures of which like ,parts are similarly designated, Figure 1 is a plan view of a transit 1n open position, showing the application of the invention thereto. Fig. 2 is a view showing.

the reverse side of one of the sight arms. Fig. 3 is a View showing the reverse side of the other sight arm. Fig. 4: is a view greatly enlarged, showing a fragmentary section of the transparent cover plate and one of the luminous indicia. Fig. 5 is a plan View of a cover plate graduated and numbered in accordance with the re uirements of the Chief of Engineers, nited States Army.

The transit or compass shown is of the type known as Bruntons pocket transit, and comprises the usual casing-,1 and cover 2 provided with the sighting arms 3 and 4,

respectively. The casing 1 has a graduated ring 5 and combined Vernier 6 and level 7 and an indicating or magnetic needle 8, and all of these parts are mounted beneath a transparent cover plate 9, preferably of glass, held in place by a ring 10. On the under side of the plate 9 is arranged a circular series of indicla, 11 of luminous paint or the like, the paint preferably; made casing and its contained elements so that i there will be no confusion of the graduations on and below the cover plate-9 when the instrument is used in the dark. The circular series of graduations 11 are spaced ten degrees apart and are numbered counter-clockwise, and like the silver or daylight circle underneath are graduated counter-clockwise from zero to three hundred and sixty degrees. To avoid the employment of unnecessary figures the zero on each of the illuminated numerals is omitted, thus 3 means thirty degrees and 8 means sixty degrees. All of the indicia, including the graduations for each ten degrees, are

made luminous and opaquely backed as described.

As shown in vFig. 5, the luminous plate is graduated and numbered in accordance with the regulations of the Chief of. Engineers, United States, Army, governing the graduation and numbering of surveying instruments for military uses. in accordance with these regulations, directions must be given in azimuth, and this term isused todefine the angular distance measured to the right of a meridiamor clockwise. in

order, therefore, that readings on an instrument of the type of mine may be taken directly from the end of the needle, the graduations of a complete circle on the compass dial must be counter-clockwise. Under the old system of graduating in quadrants, it was necessary to give a direction in at least three terms, as, for example, north 60 west; whereas under the present system the reading for the example above given, would be simply 60. As shown, the luminous graduations are spaced ten degrees apart, as insystems and for different uses. For ex- --dicated by the shorter lines, and arranged ample, for artillery service the instruments 'will he graduated in mills (6 100 mills equals 60 degrees).

The needle 8 has the whole of its north end 13 madeluminous, as indicated in solid black, but only a portion of its opposite end 14 is made luminous, as shown in the same manner, whereby the user will be able readily to distinguish the two ends of the needle in making readings of observations in the dark. I

In addition to the luminous indicia on the cover plate 9 and the luminous needle 8, the sighting arm 3 is provided on opposite sides vwlth luminous sight points 16 and 17 re- 1 spectively' adjacent the sight opening 15,

and the sight opening 18 o sighting arm 4 is similarly provided with sight points 19 and' 20.

'2 is provided with a luminous point 23.

The si ht line 21 of mirror 22 of the cover th'e dark, all of'the light emanating from the luminous indicia is projected outwardly through the cover plate, owing to the opaque backing of the indicia, leaving the interior of the casing 1 and everything below the cover plate 9, except the needle 8, in complete darkness and invisible, thus eliminating the ossibility of a confusion of readings.

v graduations are of such a size and so spaced that the aura around each one will not conoreover, the indicia, including the verge with those of the ones adjacent, thuspreventin the formation of a halo or con-' fusion of illumination which would interfere with easy observation of the indicia.

As already sufliciently indicated, the luminous indicia are placed on the back'or inside surface of the glass cover, and they are thus arranged in order to be free from atmospheric influences, as well as protected from disfigurement or erasure by surface contact with the operators hands and other objects, and also so that the diffusion of their light ma be controlled, as already explained.

arious changes in details and arrangement are contemplated as within the spirit of the invention and the scope of the claims followin What claim is 2-- 1. In a transit or the like, a transparent cover plate, luminous indicia applied to the under side of said plate and a backing of non-luminous material applied to the indicia toprevent the diffusion of the light of the indicia to the subjacent parts of the instrument.

2. In a transit or the like, a transparent cover plate, luminous indicia applied .to the under side of said plate, and an opaque substance applied -to and covering the under side of said indicia.

In testimony whereof I have hereunto set my hand this 14th day of September, A. D.

DAVID W. BRUNTON. Witnesses C. 7W. FowLER, WM. H. FINGKEL. 

